Pharmacology of Insomnia Flashcards

1
Q

Nervous structures/NTs involved in wakefulness

A
  • Peduncolopontine Tegmental ==> ACh
  • Dorsal Raphe ==> Serotonin (5HT)
  • Ascending Reticular Activating System
    • Locus Ceruleus ==> NE
    • Ventral Tegmental Area ==> DA
    • Posterior hypothalamus ==> Histamine
  • Lateral Hypothalamus ==> hypocretin
  • Basal forebrain ==> Adenosine build-up while awake
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2
Q

Nervous structures/NT involved in REM sleep

A
  • Pedunculpontine Tegmental ==> ACh
  • Anterior Hypothalamus ==> GABA (reduced compared to NREM)
  • Dorsal Raphe ==> Serotonin OFF
  • Lateral Hypothalamus ==> some hypocretin activity possible
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3
Q

Drugs actions on NTs involved in sleep/wave

A
  • _Muscarinic agonists and AChEIs _activate REM
    • antimuscarinic drugs suppress REM sleep
  • Antidepressants (SSRIs / SNRIs /TCADs) 5HT / NE in the synapse and ¯ REM sleep
  • _Amphetamines / methylphenidate _
    • ==> ↑ NE release and promote wakefulness
    • ==> ↑ DA release and promote wakefulness
  • Antihistamines promote drowsiness and sleep
  • Benzodiazepines enhance GABA and promote sleep onset / continuity
  • Adenosine antagonists (caffeine) increase alertness
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4
Q

Effects of sedative-hypnotics on sleep

A
  • positive effects
    • decrease latency of sleep onset
    • increases duration of stage 2 sleep
  • negatibe effects
    • decrease delta sleep (esp. barbiturates)
    • decrease REM sleep (esp. barbiturates)
    • tolerance
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5
Q

Benzodiazepines/NBRA/Barbiturates MOA (general)

A
  • facilitate action of GABA @ GABAA receptor-chloride channel ==> increased inhibition @ CNS
  • increased inhibition ==> promotes sleep
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6
Q

NT/drug actions @ GABAA channel

A
  • consists of combinations of alpha, beta, and gamma subunits
  • GABA incteracts w/alpha or beta ==> open chloride channel
  • GABA channels w/alpha1 subunits:
    • @ cortex
    • mediate sedative/sleep
    • site of action for benzodiazepines and “Z-drugs”
  • GABA channels w/alpha2/alpha5 subunits:
    • @ limbic system/brain stem
    • mediate anxiety
    • site of action for benzodiazepines ONLY
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7
Q

Benzodiazepines: MOA

A
  • enhance GABAA channel activity via gamma or alpha1 or alpha2/alpha5 subunit
  • ==> anxiolysis & sleep
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8
Q

Z-drugs: MOA

A
  • enhance GABAA channel activity alpha1 subunit
  • ==> sleep
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9
Q

Triazolam: class, pharmK vs. utility

A
  • Benzodiazepine
  • rapid oral absorption ==>
    • catious use in elderly (reduce dose)
  • short t1/2 = rapid elimination ==>
    • less daytime sedation
    • rebound insomnia
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10
Q

Temazepam: class, pharmK

A
  • Benzodiazepine
  • Intermediate t1/2 and slowly absorbed ==>
    • minimal effect on sleep onset
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11
Q

Flurazepam: class, pharmK

A
  • Benzodiazepine
  • very long t1/2 ==>
    • little tolerance
    • @ elderly/impaired hepatic clearance:
      • daytime sedation
      • overdosage
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12
Q

“Z-drugs”: class, pharmK

A
  • Nonbenzodiazepine Benzodiazepine “Receptor” Agonists
  • Zolpidem (Ambien) and Zaleplon (Sonata).
    • Shortest durations of action (6-8 hours) and half-lives of available agents
    • Rapid oral absorption.
  • Eszopiclone (Lunesta). Structurally different from zolpidem or zaleplon with longer t1/2 (~ 6 hrs)
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13
Q

Side effects of benzodiazepines

A
  • dose-dependents
  • overdoses rare except in combo w/alcohol or other CNS depressants
  • daytime sedation and performance impairment (esp. w/long or intermediat t1/2)
  • anterograde amnesia
  • rebound insomnia (esp. w/short-int. t1/2)
  • psychologic/physical dependence
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14
Q

Tx of benzodiazepine overdose

A
  • flumazenil (Romazicon) = benzodiazepine receptor antagonist
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15
Q

Side effects of Zolpidem

A
  • drowsiness, amnesia, dizziness, headache and GI complaints.
  • no significat next-day psychomotor performance impairment
  • Rebound effects and w/drawal or tolerance with prolonged use appear minimal
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16
Q

Side effects of Zaleplon

A
  • dizziness, headache, and somnolence
  • no next-day psychomotor impairment or rebound insomnia
17
Q

Side effects of Eszoplicone

A
  • Similar to zolpidem but longer half-life associated with increased incidence of next day psychomotor impairment with higher doses
  • FDA required lower dose for initiation
18
Q

“Z-drugs” general role in tx of insomnia

A
  • first-line agents
  • selective interaction w/alpha1 subunits of GABA receptors
  • little effect on sleep stages III/IV
  • effective and relatively safe
    • low potential for tolerance, dependence, abuse
19
Q

Zolpidem: role in insomnia tx

A
  • Effective for reducing sleep latency and nocturnal awakenings with an increase in total sleep time and efficiency
  • most widely prescribed
20
Q

Zaleplon: role in insomnia tx

A
  • sleep aid for falling back to sleep after middle-of-the-night awakenings.
  • Zaleplon can get patient back to sleep (rapid onset), yet be eliminated by morning awakening (short half-life), so no “hangover” effect.
21
Q

Eszopiclone: role in insomnia tx

A
  • safe for long term use with little or no suggestion for development of tolerance, dependence or abuse
22
Q

Benzodiazepines: role in tx of insomnia (general)

A
  • previously mainstay of pharmacotherapy for insomnia, now declining in faor of Z-drugs
    • lower safety
    • interupt sleep stages III/IV
  • still suitable for some short-term tx of insomnia
23
Q

Examples of Non-GABA sleep aids

A
  • Ramelteon
  • Trazodone
  • Diphenhydramine
  • Chloral hydrate
24
Q

Trazodone: MOA, SE

A
  • MOA: effects on 5HT neurons: inhibition of reuptake + both agonist and antagonist receptor actions
    • antidepressant
    • sedating/increased sleep continuity
  • SE:
    • oversedation/orthostasis
    • NO addiciton/tolerance
25
Q

TCADs: MOA, SE

A
  • MOA: block serotonin reuptake
    • sedating antidepressant
    • increased sleep continuity
  • SE
    • antimuscarinic activity
    • disturbed cardiac conduction
    • daytime sedation
26
Q

Ramelteon (Rozerem): MOA, SE

A
  • MOA: agonist @ melatonin receptors
    • decreased sleep latency
  • SE:
    • minor SE/low incidence
    • dizzy, somnolence, fatigue, nausea
27
Q

Antihistamines (Diphenhydramine): MOA, SE

A
  • MOA: antagonist @ histamine and muscarinic cholinergic receptors
    • ==> sedation
  • SE:
    • minimal
  • NOT recommended as insomnia tx
28
Q
A